Wednesday, January 30, 2013

Once again an off-topic post in the blog. Somehow the strange desire to share computing / IT topics occasionally took over.

Presently, I am rebuilding my IT, trying to catch up with recent technologies.

Years ago, I purchased an Acer Aspire easyStore H340. The neat little device came with 3 1TB HDDs and MS Windows Home Server. The latter, although doing its job, sucked. Finally, I decided to look for alternatives, in particular some with RAID redundancy and modern file-systems, such as ZFS.

The first alternative I found was "freeNAS". This product, along side some others, is supposed to run from flash drives or SSDs. This would helps to speed up boot and also preserves valuable HDD slots for volume data devices.
And here it comes, the H340 carries an onboard 256MB flash memory device, which is used for MS WHS recovery.
Early versions of FreeNAS were small enough to fit on this device. However, FreeNAS has evolved and grew somewhat larger.

The good new is, that there is some other product, which originates in FreeNAS and is still small enough... check out NAS4Free.

To install NAS4Free, I figure, there is only one option: equip the headless H340 with a head, i.e. a keyboard and a screen. I choose to obtain a PCIe-1x graphics card and use a USB keyboard for input.Additionally, JP3 needs to be installed!!! Do not remove the jumper at any later stage... at least my H340 would not boot NAS4Free w/o it. Contrary to JP3, the graphics card can be removed, e.g. to reduce power consumption.

Here comes the tricky bit, the H340 needs some strange tweaks to get it to boot from USB sticks, USB CD drives etc. The CMOS setup is not that straight forward, but, it will get you there. The F12-key will help to select the boot device, if it has been recognized by the system.

To get up my system, I choose to boot the NAS4Free live CD with a USB CD-drive.
The option to install an embedded system w/o swap will install the OS on the H340's internal flash drive, just about... no room to spare, all done with a screen/kb attached.

Here comes the more fancy bit.
In such a setup, you would like to go for the most senior option of storage, which presently seems to be ZFS.
The configuration of ZFS is actually not very well documented, neither at SUN, nor at NAS4Free. So, here's what I did to get ZFS up and running on an H340.

install NAS4Free from a CD using a screen and keyboard attached

reboot after installation has finished, the console should offer a possibility to use DHCP now

note the IP-address given to the H340

using a remote computer, connect to the H340 using a webbrowser

go to the "disks" menu and "import" all disks

go to the "disks format" menu and format all HDDs with ZFS

go to the "disks zfs pools" menu and create a virtual device (I used single parity raid)

go to the "disks zfs pools management" menu and create a "pool"

go to the "disks zfs datasets" menu and create a dataset using your pool(s)

go to the "disks zfs volumes" menu and create a volume using your dataset(s)

The volume(s) should now be ready to use, i.e. assign to services. Under the "services" menu, one can activate various services such as NFS, CIFS/SMB, AFP etc. Assign those services to a mount point in your volume(s).
Update: It appears not to be necessary to use zfs volumes. It is advisable to mount the dataset. Additionally, it seems a good idea to use the "dedup" feature, although caution should be taken when removing a dataset, cf. advice given by nas4free.

You'll by now be running a rather robust ZFS NAS made of relatively cheap WHS hardware.
I figure it is pretty cool that NAS4Free still fits on the onboard flash drive of the H340.

Sunday, January 20, 2013

Lucky for us, there is another kit vendor, who's kits have the potential to replace the ones of Dave.
Have a look at the KN-Q7A kits.

The 20m KN-Q7A operates with an i.f. of 4.194MHz, using a ladder filter made of standard xtals. The transceiver makes us of a moderately pulled VXO of 18.432MHz. All parts a relatively standard and well known, apart from a couple of inductors. The design makes use of subtractive mixing, which increases stability.

Here's what we can learn from Dave's PSK-series, the combination of standard crystals to result in an operating frequency near enough to the PSK bands.

30m: 4.000MHz + 6.144MHz

20m: 5.0688MHz + 9.000MHz

The only difference to the KN-Q7A is that additive mixing is used.

The 40m KN-Q7A involves two different i.f., dependent on the frequency range ordered, either 8.467MHz or 8.192MHz. The l.o. will make use of any of those frequencies: 15.360MHz, 15.418MHz, 15.500MHz, 15.536MHz or 15.570MHz. I have not yet figured out a combination to reach 7.040MHz, however, I am sure that one can be found.

Further, I am convinced that the design can easily be adapted to the 80m band. Think of 10.000-6.400 for starters.

As to QRSS/WSPR:

30m already cover the mod above

15m 4.000MHz i.f. and 25.000MHz l.o.

15m WSPR: 4.096MHz i.f. and 25.000MHz l.o.

20m could be reached by 4.000MHz i.f. and 18.000Mhz l.o.

20m WSPR: 4.096MHz i.f. and 10.000MHz l.o.

40m best option would be 4.000MHz i.f. and 11.000Mhz l.o. (alternatively 11.059Mhz)

Friday, January 4, 2013

Just a thought, a 4.000 MHz (industrial xtal) signal mixed with a 3.530 MHz (80m xtal) signal would result in 470kHz, somewhat shy of our band.

The 4MHz would make a nice intermediate frequency, with a cheap ladder filter. Tweaking QRG is hence restricted to the 3.5x MHz frequency

A couple of options

pull 80m xtal down

pen the 80m xtal down (super VXO)

A thought outside the box could be to get dividers into the equation. Douple 3.530 and you will get 7.060. As stated above, the 3.53 are just a bit too high.
Expanded Spectrum Systems sells 40m crystals, which, divided by 2, would result in in-band frequencies.

7.042 MHz => 479kHz

7.050 MHz => 475kHz

7.055 MHz => 472.5kHz

Also here, a super VXO would be an option.

For a WSPR transceiver, the 7.050 MHz option seems ideal. A small downward pull of some hundred Hz should be easily doable without compromising stability. Mind you, WSPR need a "USB dial frequency" of 474.2kHz.

Wednesday, January 2, 2013

A while ago, I built the Octaplumb octagonal RX loop, made from heavy gauge copper wire and PVC plumbing parts (see earlier posts). The loop was tuned to 504kHz, since that was what we had at the time.

Very recently, we know got a slightly different range. Hence, the center QRG of the Octaplumb had to be changed. Some experimentation showed that adding 82pF to the 680pF which are in parallel to the butterfly configed poly-vary-con.